Walker Pass Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Walker Pass Campground clear sky chart from 2005-11-05 to 2018-03-11.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
61%
16314
39%
49016
27%
16274
73%
16274
61%
20895

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
60%
777
30%
2716
26%
776
71%
776
49%
1173
January16th to endNight
56%
832
38%
2637
29%
832
70%
832
46%
1242
February1st to 15thNight
55%
759
38%
2285
28%
757
69%
757
52%
1056
February16th to endNight
48%
684
39%
2051
27%
684
67%
684
53%
944
March1st to 15thNight
48%
764
32%
2292
21%
764
65%
764
51%
1041
March16th to endNight
46%
768
38%
2007
20%
768
61%
768
56%
977
April1st to 15thNight
40%
719
37%
1799
11%
719
56%
719
56%
872
April16th to endNight
43%
720
41%
1800
12%
720
58%
720
64%
823
May1st to 15thNight
46%
578
39%
1658
18%
578
59%
578
68%
661
May16th to endNight
46%
562
37%
1685
19%
561
60%
561
63%
652
June1st to 15thNight
58%
387
39%
1467
29%
387
75%
387
74%
455
June16th to endNight
60%
360
42%
1440
36%
360
77%
360
79%
417
July1st to 15thNight
78%
340
36%
1360
37%
340
86%
340
68%
441
July16th to endNight
83%
507
40%
1537
36%
475
84%
475
66%
620
August1st to 15thNight
78%
717
39%
1790
22%
713
81%
713
81%
788
August16th to endNight
82%
764
46%
1910
28%
764
85%
764
82%
849
September1st to 15thNight
83%
720
43%
1827
29%
720
88%
720
77%
825
September16th to endNight
76%
716
50%
1980
39%
716
87%
716
83%
777
October1st to 15thNight
65%
720
41%
2007
29%
720
79%
720
67%
885
October16th to endNight
68%
768
47%
2358
39%
768
82%
768
67%
944
November1st to 15thNight
66%
760
38%
2470
32%
760
80%
760
62%
987
November16th to endNight
67%
780
41%
2535
38%
780
77%
780
61%
1030
December1st to 15thNight
61%
780
37%
2535
27%
780
75%
780
50%
1118
December16th to endNight
52%
832
34%
2870
27%
832
65%
832
43%
1318

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
211212346%73%
49602
Night
212212346%72%
49207
TransparencyDay
11%2416%29%35%
49286
Night
11%25%19%30%30%
49024
SeeingDay
415%30%31%13%3
6412
Night
28%24%32%25%6%
16324

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
5%11221435%8%63%
1552
16th to endDay
7%213322446%61%
1935
February1st to 15thDay
321222336%9%62%
1901
16th to endDay
421332345%7%62%
1709
March1st to 15thDay
22122245%7%9%61%
1904
16th to endDay
2113245%6%10%61%
2212
April1st to 15thDay
2112322348%67%
2149
16th to endDay
11112248%74%
2160
May1st to 15thDay
11112236%77%
2289
16th to endDay
211211336%74%
2429
June1st to 15thDay
11112236%79%
2490
16th to endDay
1111287%
2520
July1st to 15thDay
211111345%75%
2520
16th to endDay
222212335%72%
2519
August1st to 15thDay
11111222283%
2160
16th to endDay
111113483%
2292
September1st to 15thDay
111122481%
2133
16th to endDay
11112286%
1980
October1st to 15thDay
211212235%77%
1950
16th to endDay
222112335%75%
1866
November1st to 15thDay
212112237%73%
1719
16th to endDay
211213349%68%
1755
December1st to 15thDay
221231245%8%66%
1755
16th to endDay
331232335%8%61%
1703
January1st to 15thNight
421322335%8%63%
2716
16th to endNight
5%413213347%63%
2637
February1st to 15thNight
1223233410%63%
2281
16th to endNight
42221325%8%64%
2051
March1st to 15thNight
12123135%6%8%62%
2292
16th to endNight
11123235%5%8%64%
2007
April1st to 15thNight
1112112348%70%
1799
16th to endNight
1211236%78%
1800
May1st to 15thNight
112247%77%
1658
16th to endNight
1112236%79%
1684
June1st to 15thNight
2236%81%
1467
16th to endNight
111289%
1440
July1st to 15thNight
11111222480%
1440
16th to endNight
11121223477%
1643
August1st to 15thNight
1122385%
1800
16th to endNight
111112386%
1910
September1st to 15thNight
121122481%
1827
16th to endNight
1112387%
1980
October1st to 15thNight
21112225%77%
2007
16th to endNight
111211236%77%
2358
November1st to 15thNight
111212336%73%
2470
16th to endNight
2122123410%67%
2535
December1st to 15thNight
2212323449%64%
2535
16th to endNight
321331445%9%59%
2870

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
17%310%26%28%13%
1552
16th to endDay
22%27%23%27%16%
1935
February1st to 15thDay
15%26%24%31%18%
1901
16th to endDay
19%37%25%32%11%
1709
March1st to 15thDay
14%37%26%28%18%
1904
16th to endDay
14%29%28%26%17%
2212
April1st to 15thDay
13%36%24%34%18%
2149
16th to endDay
9%15%22%39%20%
2160
May1st to 15thDay
8%1321%32%32%
2289
16th to endDay
10%1316%42%24%
2432
June1st to 15thDay
6%1212%27%50%
2490
16th to endDay
5%1314%73%
2520
July1st to 15thDay
10%216%14%64%
2371
16th to endDay
13%229%21%50%
2363
August1st to 15thDay
8%15%19%64%
2146
16th to endDay
6%1424%62%
2292
September1st to 15thDay
8%218%22%56%
2133
16th to endDay
5%16%37%48%
1980
October1st to 15thDay
10%1113%36%37%
1950
16th to endDay
11%1213%33%37%
1866
November1st to 15thDay
11%25%20%39%21%
1719
16th to endDay
12%35%21%33%22%
1755
December1st to 15thDay
14%29%25%29%17%
1755
16th to endDay
19%410%26%24%14%
1703
January1st to 15thNight
17%38%26%31%12%
2716
16th to endNight
20%27%22%29%18%
2637
February1st to 15thNight
16%27%22%30%20%
2292
16th to endNight
16%25%28%34%13%
2051
March1st to 15thNight
14%48%25%28%18%
2292
16th to endNight
12%39%32%28%13%
2007
April1st to 15thNight
12%16%28%35%14%
1799
16th to endNight
8%1429%40%16%
1800
May1st to 15thNight
6%1224%39%25%
1659
16th to endNight
6%1422%41%22%
1685
June1st to 15thNight
41215%32%43%
1467
16th to endNight
46%19%67%
1440
July1st to 15thNight
8%17%15%65%
1360
16th to endNight
11%128%24%51%
1537
August1st to 15thNight
6%117%20%62%
1790
16th to endNight
6%15%29%57%
1910
September1st to 15thNight
8%117%24%56%
1827
16th to endNight
48%38%47%
1980
October1st to 15thNight
9%2212%35%37%
2007
16th to endNight
9%1312%34%38%
2358
November1st to 15thNight
10%2421%36%23%
2470
16th to endNight
12%15%23%31%24%
2535
December1st to 15thNight
15%38%22%29%18%
2535
16th to endNight
19%410%25%24%15%
2870

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
14%14%30%22%12%6%
90
16th to endDay
10%18%26%26%14%3
303
February1st to 15thDay
419%30%26%14%4
326
16th to endDay
9%23%34%23%8%1
290
March1st to 15thDay
9%21%32%24%10%1
312
16th to endDay
8%27%34%23%6%
288
April1st to 15thDay
12%29%28%19%7%1
269
16th to endDay
5%31%40%17%41
270
May1st to 15thDay
322%38%25%6%3
288
16th to endDay
425%29%27%10%2
330
June1st to 15thDay
414%39%30%9%
315
16th to endDay
115%29%36%14%3
315
July1st to 15thDay
1428%43%16%5%
305
16th to endDay
4224%44%18%5%
327
August1st to 15thDay
36%33%39%14%3
315
16th to endDay
5%25%41%21%5%
332
September1st to 15thDay
27%27%47%12%2
315
16th to endDay
110%28%40%17%1
315
October1st to 15thDay
413%35%33%11%
315
16th to endDay
312%28%32%18%4
282
November1st to 15thDay
39%22%28%30%5%
135
16th to endDay
214%20%37%20%3
135
December1st to 15thDay
212%28%28%22%5%
135
16th to endDay
120%21%32%19%3
105
January1st to 15thNight
5%5%21%31%25%10%
780
16th to endNight
7%8%21%32%23%7%
832
February1st to 15thNight
29%27%27%24%8%
764
16th to endNight
5%9%33%28%17%5%
684
March1st to 15thNight
212%31%30%17%5%
764
16th to endNight
215%33%27%16%3
768
April1st to 15thNight
319%33%24%15%3
719
16th to endNight
117%35%25%16%3
720
May1st to 15thNight
113%36%30%13%3
579
16th to endNight
218%30%31%17%
563
June1st to 15thNight
7%32%42%15%1
387
16th to endNight
1334%43%17%
360
July1st to 15thNight
214%45%34%2
340
16th to endNight
1110%48%37%1
507
August1st to 15thNight
16%45%32%4
717
16th to endNight
1112%33%41%9%
764
September1st to 15thNight
111%34%44%7%
720
16th to endNight
416%28%37%11%
716
October1st to 15thNight
15%23%35%24%9%
720
16th to endNight
17%17%26%31%14%
768
November1st to 15thNight
17%21%28%28%12%
760
16th to endNight
36%18%32%28%10%
780
December1st to 15thNight
49%19%35%24%6%
780
16th to endNight
49%28%28%22%6%
832
Page generated at 2018-03-12 10:28:11. Version ac04

Copyright 2018 A. Danko


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